Infant birth head circumference z-score was negatively associated with cortisol concentrations (aβ –0.01 ± 0.04 ng/ml, p < 0.05). There was a weak positive correlation between GC concentrations in HM and gestational age at birth ( r = 0.1, p < 0.05). At 4m CA, higher maternal perceived stress was negatively associated with GC concentrations in HM (cortisol adjusted beta-coefficient –0.01 ± 0.01 ng/ml, p = 0.05 and cortisone aβ –0.1 ± 0.03 ng/ml, p = 0.01), whereas higher postpartum depression and maternal obesity were associated with lower cortisone concentrations (aβ –0.1 ± 0.04 ng/ml p < 0.05 MD –0.1 ± 0.04 ng/ml p < 0.05, respectively). Compared to no antenatal corticosteroid (ANS), a complete course of ANS was associated with lower GC concentrations in HM through to 4m CA (cortisol: MD –0.3 ± 0.1 ng/ml, p < 0.01 cortisone MD –1.8 ± 0.4 ng/ml, p < 0.001). Cortisone concentration did not change across lactation but was higher than cortisol throughout. Cortisol concentrations in HM increased from postnatal day 5–4m CA (mean difference 0.6 ± 0.1 ng/ml, p < 0.001).

Results: 170 mothers of 191 infants provided 354 HM samples.

Relationships between GCs in HM and both maternal and infant characteristics were investigated using Spearman’s correlations and linear mixed models. GCs in HM were measured by liquid chromatography-tandem mass spectrometry. Materials and methods: HM samples were collected on postnatal day 5 and 10 and at 4 months’ corrected age (4m CA) in a cohort of moderate- and late-preterm infants. GCs are present in human milk (HM), but whether maternal and infant factors are associated with HM GC concentration following preterm birth is unclear.

2Neonatal Unit, Kidz First, Middlemore Hospital, Auckland, New Zealandīackground: Glucocorticoids (GCs), cortisol and cortisone, are essential regulators of many physiological responses, including immunity, stress and mammary gland function.

1Liggins Institute, University of Auckland, Auckland, New Zealand.

Bloomfield 1* for the DIAMOND study group Mariana Muelbert 1 Tanith Alexander 1,2 Mark H.

Auto keyboard presser 2.1.0.6 full